Check the signature...

The bottom of the sculptures may have bits of writing and remains of paper labels or even those crazy tape lable maker things from the 1960s...

 sometimes there is no name at all, just some initials, JEM or JM welded into the wood or metal.

Here's some ink signatures. He would simply write with a marker or pen, or sometimes do pen-and-ink calligraphy.

sometimes there's only a title: "New City" was a popular series he did, and he did a series of "Icarus" figures and women-with-bird series.  There is usually a date. In the 1950s, he would just put the last digit ('7" means 1957.) starting with 1960 he put the last two digits.